I'd guess you either got lucky then, or it didn't look suspicious to them (e.g. your first time doing it, or there wasn't a huge fare difference from the ticket

I'd guess you either got lucky then, or it didn't look suspicious to them (e.g. your first time doing it, or there wasn't a huge fare difference from the ticket you "should've" bought). It used to be easy to use this trick, but airlines much more often cancel itineraries if you skip a portion now, since the contract terms specifically ban "hidden-city ticketing" and "throwaway ticketing". Was a bit of a brouhaha a few years ago at flyertalk when it started happening. But of course airlines don't disclose what exactly triggers enforcement.